Luminaire



Oct. 14, 1941. c. A. B. HALVORSON 2,259,107

LUMINAIRE Filed Aug. 15, 1938 lrwven tow Cromwell A. B'JHaI Orson, y MHis Attorney ll'l MI Patented Oct. 14, 1941 LUMINAIRE Cromwell A. B.Halvorson, Lynn, Mass, assignor to General Electric Company, acorporation of New York Application August 13, 1938, Serial No. 224,757I 1 Claim.

My invention relates to street lighting luminaires, and moreparticularly to luminaires in which electric discharge lamps are used asa primary source of light.

One object of my invention is to eliminate the outage period due tomomentary current inter ruptions in luminaires equipped with gaseousdischarge lamps.

Another object of my invention is to provide an improved arrangement ofelements within a luminaire provided with more than one lamp.

For a better understanding of my invention together with other andfurther objects thereof, reference is had to the following descriptiontaken in connection with the accompanying drawing, and. its scope wi1lbe pointed out in the appended claim.

In view of, the high efiiciency of gaseous discharge lamps and thepossibility of obtaining a large amount of light from relatively smallunits, it is desirable to use such a light source in street lightingluminaires. For such service, however, it is necessary that the lamps becontinually in operation during the time that current is supplied to thelamp, and that the outage periods be kept at a minimum. It is one of thecharacteristics of gaseous discharge lampsthat they will extinguish atthe occurrence of only a momentary interruption of current supply, orupon the occurrence of a voltage disturbance, and will not functionagain for a substantial period thereafter, although the current supplyis immediately reestablished. One of the types of gaseous dischargelamps which is desirable for this'service is the type in which a fillingof gas such as neon or argon is used with a globule of mercury. Themercury is vaporized, and the vapor is ionized during operation, the gaspressure in the lamp being anywhere from one to many times theatmospheric pressure. Lamps of the above-described type, which operateat several times atmospheric pressure, are disclosed and claimed inUnited States Patent No. 2,094,694.

It is a general characteristic of gaseous discharge lamps that they willoperate at a voltage which is lower than the voltage required to startoperation of the lamps. It is still another characteristic of lamps ofthe type disclosed in the above-mentioned patent that if operationshould momentarily cease, the lamp will not immediately resume operationunless cooled to a temperature which is substantially below operatingtemperature.

In order to provide a luminaire suitable for street lighting service, Itake advantage of the second of the above three mentionedcharacteristics and overcome the disadvantages of-the first and last ofthe above-mentioned characteristics by providing in my luminaire twodischarge lamps connected in parallel to a series circuit. With thisarrangement, a starting potential is provided which rises up to a valuehigher than the operating potential until a value is reached at whichone of the lamps starts operating. Since it very rarely occurs that twolamps will start at exactly the same voltage, only one of the lampsstarts, and the supply voltage, as a result of the current flowing inthe circuit, immediately drops so that the second lamp will not receivea sufliciently high potential to start it. The second lamp is thereforea standby lamp which is ready for operation in case the operating lampis extinguished due to a momentary interruption of current or potentialdrop sufiicient to interrupt the operation of the one lamp. With thisarrangement, therefore, it is not necessary to wait for the one lamp tocool ofi before the luminaireagain resumes operation. 7

In order to adapt my luminaire for all outdoor temperatures, I provide,in addition to the two discharge lamps connected in parallel to a seriescircuit, an incandescent filament lamp which I arrange to keep energizedfor a short period after each resumption of current supply. When thelamps are turned on in the evening, the incan descent lamp is fullyenergized immediately. When lamps of the type disclosed in theabovementioned patent are used, there is no starting period, and thelamps reach full brilliance immediately. In some of the other types ofgaseous discharge lamps, however, it is necessary to raise thetemperature of the lamp before the gas becomes luminous, and in somelamps a starting period occurs during which the lamps are not at fullbrilliance. By including an incandescent filament lamp which attainsfull brilliance immediately, I provide a supplemental sourceofillumination for such a starting period, and simultaneously provide aheating element which, if necessary, raises the temperature of thegaseous discharge lamp to a value at which starting isgreatlyfacilitated.

In accordance with another phase of my invention, the discharge lampsand the incandescent lamp, together with its control relay, are mountedwithin the luminaire in a simplified manner so as to provide anefficient light fiux distribution and simultaneously to provide asimplified structure which facilitates manufacture of the luminaire ofmy invention.

Referring to Fig. 1 in detail, I have shown a conventional streetlighting luminaire comprising a cap 5, a conoidal reflector 6, and asubstantially semi-spherical globe 'I. The reflector is attached to thecap by two latch mechanisms attached to the reflector 6 and comprising aring 8 operated by a cam lever 9 and engaging a hook IE! on the cap 5.The lower edge 6' of the reflector overlaps the edge of the globe and ismolded thereover by a spinning process which effects such close contactbetween the two that a substantially dust-tight joint is provided.

Within the cap 5 a bracket II is attached at its upper end to the end ofa pipe I2. This pipe supports the entire luminaire and is threadedthrough a suitable opening at the upper end of the cap 5.

The bracket II is made of a narrow band of sheet metal which is suitablybent so as to project into the reflector and support the lamps of theluminaire in suitable relationship to this reflector. The upper end I3thereof is horizontal so as to receive the pipe I2 and is at rightangles to the part I4 which projects vertically, near the wall of thecap, to the upper end of the reflector. The adjacent part I5 is bent atan angle to the vertical so as to project toward the wall of thereflector at its lower end and there joins a vertical part I6. Upon thispart of the bracket 2. socket I1 is mounted for an incandescent lamp I8.Below this socket I! on a widened part I9 of the bracket two sockets areattached side by side to support two discharge lamps H and 22. Thesedischarge lamps are supported horizontally and parallel to each other inthe focal region of the reflector 6. The incandescent lamp I8 issupported horizontally above the discharge lamps. The relative locationof the incandescent lamp I8 and the discharge lamps 2| and 22 within thereflector is such that light from the in candescent lamp is projectedand reflected past the discharge lamps, and a part of the heat from theincandescent lamp is transferred to the discharge lamps. Furthermore,this compact arrangement of all the lamps upon a single bracket permitsthe use of a standard reflector and globe assembly in which the openingin the globe is relatively small. To remove the reflector, it isunlatched and after being lowered to the incandescent lamp, may be movedhorizontally to clear all the lamps simultaneously.

In Fig. 2 I have diagrammatically illustrated the manner of supplyingcurrent to the discharge lamps 2| and 22 and to the incandescent lampI8. In this figure I have shown a portion of a series circuit 25 havingconnected therein the primary winding 26 of a series transformer 21. Thedischarge lamps 2I and 22 are connected in parallel to the terminals ofa secondary winding 28 of the transformer 21. The incandescent lamp isconnected to the series circuit 25 through a circuit which is controlledthrough a combination magnetic and thermostatic relay 29 which isattached to the vertical part I 4 of the bracket I I within the cap 5.The relay is provided with a movable contact 30 normally in contact witha stationary contact 3| and thereby establishing a circuit from aterminal 32 on one side of the primary winding 26 through a resistor 33to the lamp I8, and through conductors 34 and 35 to a terminal 36 on theother side of the winding 26. The potential drop between the terminals32 and 36 is therefore the potential drop across the transformer primarywinding 28. The movable contact 30 is held in engagement with thestationary contact 3| by a block 31 mounted on the end of a thermostaticelement 38. The thermostatic element when at normal temperature movesthe block into the path of the movable contact 30, thereby preventingthe arm from moving out of engagement with the stationary contact 3|.When current flows through the circuit which is then established, theresistor 33 transfers heat to the thermostatic element 38 and causes thelatter to warp and move the block 31 to disengage the end of the movablecontact 30. When the movable contact is so released a magnet 40connected to the series circuit by conductor 35 and by a conductor 4|moves the contact and holds it out of engagement with the contact 3|,thereby breaking the circuit to the incandescent lamp. The potential onthe coil 40 is also the potential drop across the transformer winding26, conductors 35 and 4| being connected to the series circuit onopposite sides of the winding 26. The time period for releasing thecontact 30 is calculated to be of sufficient length to maintain theincandescent lamp energized during the starting period during which thedischarge lamp attains full brilliancy. This period, of course, isadjusted for the particular type of lamp used. In operation, therefore,when current is first supplied to the series circuit 25 in the evening,the incandescent lamp I6 is energized, and due to the characteristics ofa series transformer the potential across the lamps 2| and 22 risesuntil current flows through one of the lamps. As soon as current beginsto flow the potential drops to a lower value which is, of course, de-

. pendent upon the characteristics ofthe transformer and of the lamp,and remains at that value until a disturbance in the current supplyextinguishes the discharge lamp.

The incandescent lamp, of course, is immediately energized upon thebeginning of current flow, and remains energized for a predeterminedperiod until the thermostatic element 38 releases the movable contact30. The magnet 40 then attracts the arm, to break the circuit of theincandescent lamp and holds the contact as long as current flows in thecircuit 25. If thereafter a current interruption is only momentary, themagnet 40 releases the relay contact which is then pulled back into itsnormal position by a spring to reestablish the incandescent lampcircuit. Simultaneously, current ceases to flow through the dischargelamp and the voltage of the secondary winding 28 immediately rises tostarting value, but due to the high temperature of the discharge lampwhich was in operation the same lamp will not resume operation. Thesecond lamp connected in parallel thereto, however, will start up atapproximately the voltage at which the first lamp started and willsupply the necessary light flux. With this arrangement, therefore,interruptions of current of only short duration do not fully interruptthe light output for any period longer than the actual interruption ofthe current supply. Furthermore, dueto the energization of theincandescent lamp during the beginning of operation of the luminaire,and subsequent to each current interruption, light flux is obtainedduring the starting period of the lamps, and simultaneously heat isobtained which will facilitate the starting of the discharge lamp atextremely low temperatures.

In Fig. 3 I have illustrated the relay 29 in greater detail. The relaybody 42 is moulded of a suitable insulating compound. It supports themagnet 40 and a pivot member 43 for a contact arm 44 to which the movingcontact 30 is attached. A spring 45 tends to turn the contact armclockwise about its pivot member 43 and holds the contacts 30 and 3! inengagement. The arm 44 is provided with an arc shield 45 upon which aprojection 41 is provided which engages the block 31 on the thermostaticelement 38. The thermostatic element is attached to the upper end of thebody 42 with the heating resistor 33 underneath it. As long as thethermostat is at normal temperature the block 31 moves into the path ofprojection 41 and prevents the energized magnet from separating contacts3i] and 3|. When the thermostat is heated it flexes and the magnet 40overcomes the pull of the spring 45 to separate the contacts. Whenmagnet 40 becomes deenergized, due to current failure, the spring 45pulls the projection 41 under the wedge-shaped block so that the latterwill again snap over the end of the projection and thereby start anothersequence of operation.

In Fig. 4 I have illustrated a modified diagram. In this modificationthe incandescent lamp is energized only as long as the discharge lampsdo not consume the normal operating current and therefore do not producesufficient light flux. This condition occurs, with some discharge lamps,during a short period when potential is first applied to the lamps. Inthis arrangement a relay magnet is connected in series with thedischarge lamps 2| and 22 across the output terminals of anauto-transformer 5|. The moving contact 52 of this relay normally closesa circuit through the incandescent lamp I8. This circuit may be tracedfrom terminal 53 at one end of the auto-transformer winding throughconductors 54 and 55 to the lamp l8 and from the lamp through conductor56, relay contacts 51, 52, 58 and conductor 59 to terminal 60 on theinput side of the transformer 5|. In this arrangement the incandescentlamp remains energized as long as the relay magnet coil 50 isdeenergized. This occurs when less than the normal operating currentflows through either of the discharge lamps. When normal current doesflow through either lamp the relay operates, the circuit through theincandescent lamp is broken, and the lamp is extinguished. Thisarrangement therefore provides the light of the incandescent lamp duringthe starting period of the discharge lamps in a manner directlyresponsive to the current flow through the discharge lamps instead offor a definite time period as in the first instance described inconnection with Figs. 1, 2 and 3. This arrangement is suitable fordischarge lamps in which light output is directly proportional to thecurrent flow and in which, therefore, full brilliance is obtained assoon as 4 normal operating current flows through the lamp.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

In a street lighting luminaire, the combination of a conoidal reflector,a supporting cap therefor, a plurality of discharge lamps mountedhorizontally in the focal region of said reflector, an incandescent lampmounted above said discharge lamps in heat exchange relation to saiddischarge lamps, a control relay operable'to control said incandescentlamp, and a bracket mounted at one end in said cap and projectingadjacent the surface of said reflector to the focal region of saidreflector, said bracket having mounted thereon said incandescent anddischarge lamps and said relay.

CROMWELL A. B. I-IALVORSON.

